Suspension 101 questions

[stephen low]

I'm back with a few more suspension queries guys but with some pics. now

Started to pull front suspension apart to reset properly and have a few queries, like:

Upper wishbone arms seem to have slightly different offsets from the pivot arm. This is evident off the photo as the square is central on the pivot arm between the arms but is offset slightly once at the ball joint end. Or is this just the movement possible through the rubber bushes?

Attachment 13128

As shown in the pic. the arms are from the drivers side with the circular castings for bolt attachment near the upper ball joint location facing downwards. Is this the correct orientation for these arms? What did the bolts originally hold in the jag set up?

Also took a pic at the upper pivot shaft attachment to the chassis.

Attachment 13126

You can see the 6 - 8mm gap between the chassis frame and the rear face of the pivot shaft, achieved by large spacers on each bolt. I've been told to mount the pivot shaft directly against the chassis frame. This would clearly affect the camber of the wheels and I'm not sure whether the use of the spacers or not in this GForce kit is correct. Can anyone help here? I'm assuming the shims were actually from the jag set up but are perhaps not needed in the GForce construction - HELP!!

Also thought about the steering linkage and the next photo shows the connecting track rod end without any form of locking nut on the threaded section. Isn't there normally some form of locking made here?

Attachment 13127

A question on the upper ball joint, unlike the lower that can be adjusted by shims, do I presume if there is any play in the joint in a vertical direction when mounted that this is normal or a sign of wear?

Both the steering and upper ball joint dust rubbers, both sides, have failed so I need to replace either the dust rubbers or the whole joint assemblies. The steering joints seem fine, it's just whether the upper joints normally move as they do or not.

Here's hoping someone can help.

Cheers

[400TT]

1. If you pulled those top arms apart and sit the pivot end flat on the ground(with hole facing up) and measure up to where they bend at the end where the ball joint mounts, both arms measure the same that way. The way you are measuring them will always be affected by those bushes. According to the jag manual this is how you determine if they are still straight.

2. That's where the camber adjusting shims go. Personally how close does the camber look, it would be nice if those spacers were cut out on one side so they could be slide off without removing the mounting bolts. When you take it for a wheel alignment they are fit appropriate sized shims that just slide in.

3. Yep, just buy a nut for that steering linkage, so you can tighten it against the end of the tie-rod end. As you guessed.

4. New upper ball joints don't have any play. Also new lower jag ball joints don't seem to need shimming any longer, they are non-shim ball joints now. Well mine were not shim ones.

5. I think you can just replace the boot over that steering joint. What brand/model column & rack are you using out of interest? I don't think you can get those upper control arm ball joint boots separately, but sounds if those joints were 2nd hand and ordinary anyway. New ones would be a good idea. They range in price from $50 - $80ea depending on where you buy and the quality of the joints you buy. I hope you have also or will buy new wheel bearings etc.

Have I missed anything.

Also make sure you have castle nuts/nylon lock nuts on all those suspension bolts & steering bolts things like tie rod ends, steering rack mount bolts, steering uni bolts etc etc. If they don't have nuts(bolts only), make sure you use spring washers e.g. caliper mounting bolts, tie-rod arm bolt etc.

[Rebel1]

What Craig said plus:

1. Series 1 jag upper arms are handed..ie., a front one and a rear one. If you're not sure what you have send me your email and I'll send you some pages from the Jag manual.

What lower arm do you have?. Series 1 is different to series 11. They should be from the same series.

2. Toss the jag spacers and use hardened washers to set your camber. when you're got it right you can machine up some solid spacers.

Advice: Get all new ball joints and rubber bushes.

Don't torque the lower a-arm pivot shaft until car weight is on the front end.

Spend time getting the camber right....You might find the car handles better with a slight neg camber whilst driving straight.

Dunno about the g-force but the RMC needs a spacer between the steering rack and chassis. ie.....lower the rack so the steering arm and lower a-arm are somewhat parallel and move thru the same arc.

Best of luck

[stephen low]

Thanks Guys all usefull knowledge.

The kit was part built when I got it, ie had suspension and steering rack mounted. As fas as I know S2 & 3 jag suspension front and rear and shortened commodore rack all std GForce for the time (1997). So no handed arms as the variance I have pictured is very small. Les are the handed arms significantly different ie you would need to be blind not to be able to tell?

Not sure if the various joints were new from the start but the way the rubbers on both upper ball and steering joints have failed tends to suggest not. With that in mind how would I test the lower joint for acceptability or replacement?

Not even sure what the steering ball joint is off may have to front a jag place for comment.

Had already read about not torquing up certain nuts without car weight on the suspension, why is that?

Steering rack is already lowered so I have adjustment both up and down to play with for bump steer elimination purposes. That's one for later though.

Presuming worst case for the 4 jag ball joints, is there a package set one can buy to get all four at once? No sense dicking around on this I think.

Cheers

[CHANMADD]

Those upper arms ARE different. The one with more angle on it goes on towards the front of the car.IE: it pushes the ball joint towards the rear of the car --- CASTOR--,is then adjusted by putting shims between the ball joint and the arms either more in the front or back to adjust the castor.Be very sure that there is no tension on those arms when you have the castor right,in other words there should be shims on both sides of the ball joint.The jag top bushing have Torrington bearings in them (Why I would never change them for a solid bush).The little mounting holes should face down,there was a little screwed in rubber bush for the bump stop in the jag. I put a piece of flat steel bar across those and mounted the jag stop that came out of that hole to the frame and that is now my bump stop.It has worked well.As said do not tighten the bottom until its on the ground with all the weight of the car on the springs.That jag front end is hard to beat.Tightening the lower at the end ensures that the rubber is not unduly stressed and can also supply some damping.

[Rebel1]

Stephen, yes there is a huge difference. Here are the differences between the upper arms.

This measurement is from a line projected from the face that the upper ball joint bolts to the pivot shaft. Then measure from that point to the inside of the upper arm.

upper arms:
Series 1 front arm = 2.38" (6.04cm.)
Series 1 rear arm = 1.75" (4.45cm.)
Series 2 ( both arms same) 2.10" (5.3cm.)

Send ya email addy and I'll send you the pages.

Cheers

[Tenrocca]

A few of us CR Sydney locals love this jag upper arm discussion - The CR is supposed to have S2\3 arms, when I got mine they were like yours, and uncle Les helped get me sorted on that as I scratched my head for a while on what way they should go. I believe one of our grand masters (ie. one with a completed car) has the series 1 arms on his, always a fun discussion on which ones are "right"- I think the geometry is probably wrong with either ones though .

If you dont mind ebay do a search for jag ball joints - I think thats where I got mine. Im too scared to ask at repco for part prices.

http://cgi.ebay.com/ebaymotors/Jagua...spagenameZWDVW

[400TT]

Gee, I just totally ignored Series 1. Didn't think anyone would be using them now. Well I suppose not on purpose anyway.

Everything I said above applies to series 2/3.

There is a variation in lower arm designs within Series 2 as well. Which I have just recently found out. Same with tie rod lever arms. Makes finding matching parts a pain. It's ok if you are just buying a complete front set.

[Rebel1]

Originally Posted by 400TT

Gee, I just totally ignored Series 1. Didn't think anyone would be using them now. Well I suppose not on purpose anyway.

Everything I said above applies to series 2/3.

There is a variation in lower arm designs within Series 2 as well. Which I have just recently found out. Same with tie rod lever arms. Makes finding matching parts a pain. It's ok if you are just buying a complete front set.

And the uprights are slightly different.

But....knowing these differences can make setting the front geometry a little easier.

ie....If you want to reduce caster if using the series 11 uppers then use a series 1 lower arm. This swop will also increase neg camber but it's easier with the shims.

If you have series 1 lowers and want to increase caster then change to series 11 lowers.

If you have series 1 uppers you can swop them to increase/decrease caster.

Keep in mind that most kit manufacturers copy the Jag geometry...problem is a jag weighs 4832Lbs(2192 Kg).

So a bit of fiddling is needed for our lighter cars.

[RoyTheBoy]

Hi Stephen,
Part numbers for Series 2 upper wishbones are as follows:
Front = C.38105 (front side of Vehicle)
Rear = C.38104 (rear side of vehicle)

There are 2 shim sizes (as per parts manual) which are:
C.1919/1 = .031"
C.1919/3 = .128"

Hope this helps :-)

Regards Roy

[RoyTheBoy]

Forgot to mention... My chassis is set up for Series 2 and takes the stock shims I mentioned in my last post. I had another look at your pic and 6mm seems a little excessive considering, mentioned, the G-Force is designed for the Jag suspension. You should only require shims for fine adjustment.

Regards

Roy

[Rebel1]

Originally Posted by RoyTheBoy

Forgot to mention... My chassis is set up for Series 2 and takes the stock castor shims I mentioned in my last post. I had another look at your pic and 6mm seems a little excessive considering, mentioned, the G-Force is designed for the Jag suspension. You should only require shims for fine adjustment.

Regards

Roy

Not totally true.

Mine is set for 0 camber ( ie exactly 90 degrees to a flat surface) when sitting level and looks exactly like Stephens except I have series 11 uppers.

ie. at least 1/4" (6mm) of spacers between mount and pivot shaft.

Standard Jag shims are : 1/32" (.8mm), 1/16" (1.6mm) and 1/8" (3.2mm).

each 1/16" will alter camber by 1/4 degree.

However, as per earlier post, forget the standard jag shims as some kit manufacturers used chassis jigs which left a lot to be desired so the accuracy of placement of inner mount is suspect.

Cheers

[CHANMADD]

From above, you probably have Series 2,lower arms and Series 1 uppers.Depends what you want your front track to be.the Series1 is narrower and also uses not vented rotors. I run Series 1 with not vented but I have only ever experienced fade after a lot of laps on a track. Series 1 is lighter also.It's a choice I suppose.Also the rears I used are from a 68 or there about "S" type,from the factory correct length.
1.5 degrees neg camber all around , and toe all 4 wheels in.

[Rebel1]

CHANMADD, I wanna thank you for the comment re toe in of rear suspension.

I have always recommended rear toe in, as I found on cobras I have worked on in a past life that it made such a difference to handling.

However, I have often been met with debate.

Cheers

[CHANMADD]

The toe in ,to me anyway, makes all the difference in a Cobra's handling.My cars handling is really great,came 1st,2nd and 3rd in road race events in S.A.

[stephen low]

Thanks guys a lot of great info. but now I'm really confused and will have to measure the arms to clarify what I have.

Do the S1 and S2/3 arms look much different?

I ask as the GF manual says the chassis is designed for S2/3 suspension, I have vented front brakes and S2/3 lower arm and am guessing the original constructors would have followed the guidance of GF. They may have unwittingly bought S1 uppers, can this be decided just by visual inspection?

If it proves I have S1 uppers, I gather I can still achieve a suitable set up, is this correct?

Given I will have to look at the rear as well at some time, why do you recomment rear toe in?

What effect does it appear to have/cause to these cars?

How much toe in have you guys used on the rear?

At least I know for sure that my rear brakes are S2/3 I have an old receipt for their repair!

Cheers

[CHANMADD]

Because a Cobra is a short wheelbase car and funny things in the handling department start to happen when the track(width) starts approaching the wheelbase, Imagine driving a square car? With my setup I was always in the top 3 on road race courses in South Africa Cobra Club meetings.(Pissed a lot of guys off)

Well because of this I have found that 1.5 degrees of negative camber on each wheel ,front and back,and 1.5 degrees toe in on each wheel will make the car handle just right. Now of course we need to dial in some castor ,that makes the car self center ,so also I like about 2 degrees of castor on the front wheels. Obviously if you are running a “live” axle at the rear you have no rear adjustments other than to make sure that the triangulation is right ,which of course is important on all cars.If the triangulation is out the car will go down the road like a crab (you know).

[Tenrocca]

Stephen,

Heres a pic of series 1 arms, you can see the difference when the front arm is at the back and back at the front as Ive layed the left hand side on top of the right hand side:



Heres the series 2\3 arms I have:



See how they kink in a bit just after the pivot bolt thingy (technical term). The difference between using series 2\3 arms (which are the same dimensions front and back) and the series 1 arms, is that the series 1 arms will place the upper ball joint 8.5mm further back.

The jury is out on whether series 2\3 arms come in a "straight" design, the place I got mine from said that they had not seen series 2\3 arms straight like series 1.

Cheers.

[Rebel1]

Steve, I have sent the manual pages showing the differences in the arms. ( you may have got it twice )

Together with the above pics from Tenrocca you should be able to identify what you have.

If I remember correctly the problem that Tenrocca was trying to identify was clearance for his springs in the CR. The G-force and RMC don't have the same problem as the spring is mounted under the top pivot bar.

However, Tenrocca's pics show the difference achieved in caster between the two series. This can be used to your advantage. I am positive that series 2/3 did not come in a kinked design.

I would just make sure that the components you have are from the same series and go from there.

Cheers

[Rebel1]

Small observation of Tenrocca pics.

The outside bolt attaching the top ball joint (round head) should have the head to the front of the ball joint for clearance with the tyre at full lock

Cheers.